Cooler unit



y 19, 1966 B. PORTER ETAL COOLER UNIT Filed Feb. 19, 1960 j w H W m MR n nEHv A To IHRRW 0A OIL C NM y mw BM 4 w H United States Patent 3,261,180 COOLER UNIT Brian Porter, 137 Garden Ave., South Hatfield, England, and William A. Hoyes, 78 Leigh Sinton Road, Malvern, England Filed Feb. 19, 1960, Ser. No. 9,996 Claims priority, application Great Britain, Feb. 20, 1959, 5,860/59 7 Claims. (Cl. 62-514) This invention relates to cooling and seeks to provide a cooler unit having the capability of cooling, adapted, upon operation, rapidly to cool an object of small thermal inertia in thermal contact with the unit and to maintain a low temperature for a limited period of time.

Such an object may be, for example, a semiconductor detector of infrared radiations. To increase the sensi tivity of detection, it is advantageous to cool the semiconductor below 0 C. and preferably to a temperature below -30 C. To prevent false indications due to subsequent temperature rise of the semiconductor, it is also advantageous to maintain the low temperature at least for the operative period of detection.

According to the invention, a cooler unit having the capability of cooling comprises a temporarily sealed container divided into two compartments, filled or substantially filled with liquid coolant, an open transfer tube for coolant extending between the two compartments, a temporarily sealed exhaust tube leading from one compartment, means to open the exhaust tube external to the container, and a liquid-restrictive packing through which coolant passes to escape from the exhaust tube.

Preferably, the packing is contained in the one compartment from which the exhaust tube leads. Suitable packings are, for example, silica wool and glass wool.

Advantageosuly the transfer tube is restrictive compared to the exhaust tube. For this purpose, the transfer tube may be narrow throughout its length or contain a narrow restriction. It may, alternatively, incorporate both forms of restriction.

If the end of the one compartment is to be cooled, the transfer tube may extend from that end or from a position adjacent that end. In this case, the end of the transfer tube may be secured to that end and have side apertures for the passage of coolant. In order to reduce spillage of liquid refrigerant the transfer tube may extend to a position adjacent the end of the other compartment remote from that end of the one compartment. The exhaust tube may lead from a position adjacent that end of the one compartment.

Conveniently, the container may have a common dividing wall through which the transfer tube extends. The exhaust tube may also extend through the common dividing wall.

The means to open the exhaust tube may include a frangible portion external to the container.

The scope of the invention is defined by the appended claims; and how it can be carried into effect is hereinafter particularly described with reference to the accompanying drawings, wherein:

FIGURE 1 is a longitudinal cross section of one embodiment of a cooler unit according to the invention in combination with a detector cell;

FIGURE 2 is a cross section on the line IIII of FIG- URE 1;

FIGURE 3 is a cross section on the line III-III of FIGURE 2;

FIGURE 4 is a cross section on the line IVIV of FIGURE 2; and

FIGURE 5 is a cross section of a second embodiment of cooler unit according to the invention.

The detector cell shown in FIGURES l to 4, comprises a cylindrical envelope of iron-nickel-cobalt alloy formed in two parts 10 and 11. The part 10 is in the shape of a top hat and has a closed end 12 and a radial flange 13 by which the combined unit and cell can be mounted. The part 11 is an open-ended cylinder which fits into and is sealed to the part 10 at one end and has its other end closed by a transparent closure 14. Electrical leads 15 pass through seals 16 in the part 10 and are connected to i4semiconductor/detector mounted adjacent the closure The cell so far described does not form part of this invention but is merely one example of an object of small thermal inertia to which the invention is applicable.

The cooler unit 20 comprises a container formed in two cylindrical parts 21 and 22 of iron-nickel-cobalt alloy. The part 21 has a closed end 23 and is longer and of slightly smaller diameter than the part 22. The part 22 has a closed end 24 and the parts 21 and 22 are inte-rfitted and sealed. The semiconductor detector is mounted on the closed end 23 in close proximity to the closure 14. A metal diaphragm 25 is secured across the part 21 to divide the container into two compartments 26 and 27 separated by a common dividing wall.

An open metal transfer tube 28 extends through a sealed aperture in the diaphragm 25 and affords communication between the compartments 26 and 27. The tube 28 has its one end secured to the central part of the end 23 on the opposite side to the detector. A diametrical slot 29 (FIGURES 3 and 4) is formed in the one end of the tube 28 and prevents closure of that end. The other end of the tube 28 is open and located adjacent the end 24 of the compartment 27 remote from the end 23 of the compartment 26.

An exhaust tube 30 also extends through a sealed aperture in the diaphragm 25 and has one open end adjacent the end 23 of the compartment 26. Inside the compartment 27, the tube 30 is bent and passes radially through a German silver bush 31 in a peripheral hole in the part 22 and a similar aligned bush in a peripheral hole in the part 10. Communication betwen the compartment 26 and the exterior of the detector cell is thus alforded, all the connections being sealed. Secured on the end of the tube 30 outside the cell is an externally threaded sleeve 33 of German silver.

Besides the tubes 28 and 30, the compartment 26 also contains a packing 38 of silica or glass Wool.

A second pair of aligned German silver bushes 34 and 35 (FIGURES 2 and 4) are mounted in peripheral holes in the parts 10 and 22. A short inlet pipe 36 is sealed into the bushes 34 and 35 and affords communication between the compartment 27 and the exterior of the detector cell. An externally threaded sleeve 37 of German silver is secured on the end of the pipe 36 outside the cell. The cooler unit 20 is accurately located and mounted within the cell by the pipe 36 and tube 30.

The transfer tube 28 is narrow and the slot 29 small so as to set up a restriction to the passage of coolant as compared to the exhaust tube 30 which is comparatively wide.

The cooler unit is filled with liquid coolant, such as Freon 13, Freon 22, or Freon 12, which boils at a desired low temperature at an ambient pressure corresponding to that likely to be encountered when cooling is required.

In this specification and the appended claims, the term coolant is used in this sense.

The filling takes place through the inlet pipe 36, and after the compartment 27 is full, liquid passes through the transfer tube' 28 into the compartment 26. After the compartment 26 is full, liquid emergesthrough the exhaust tube 30. The exhaust tube 30 is then sealed with a frangible seal, for example in the form of a glass bulb 38'. The inlet pipe is then sealed. The container of the Patented July 19, 1966- be blown out through the exhaust tube.

3 unit 20'is now sealed and substantially filled with liquid coolant under a pressure equal to the vapor pressure of the refrigerant at the ambient temperature. The detector cell is evacuated as thoroughly as possible.

In use, to initiate operation to cool the semi-conductor detector on the end 23 of the compartment 26, the frangible glass bulb is broken by release of a conventional detent-held spring-urged plunger 39. There is an immediate fiow of coolant through the exhaust tube 30 from the compartment 26 due to the pressure in the unit 20 and boiling of the liquid coolant.

This gives a rapid cooling to the end 23 of the compartment 26 and to the semiconductor which is in good thermal contact therewith. Further supplies of coolant from the compartment 27 pass through the transfer tube 28 to the compartment 26 and thence to the exhaust tube 30. When the boiling temperature of the coolant at ambient pressure is reached (that is the desired low temperature to be maintained), boiling of the coolant in the compartment 27 continues, at a slower rate vapor escaping through the transfer and exhaust tubes. The low temperature is thus maintained until all liquid coolant has boiled away. Thereafter the temperature gradually rises to ambient temperature.

The duration of the limited period of time during which cooling is maintained is largely determined by the amount of liquid coolant left in the container after the initial rapid cooling caused by the rapid escape of coolant through the exhaust tube. To leave as much liquid as possible, the escaping coolant should be in the form of vapour and the silica or glass wool packing assists towards this. The wool acts as a liquidrestrictive packing and traps much of the liquid which would, in its absence, It will be under stood that other materials may be used inert to the coolant and such as to present a difiicult path for liquid whilst permitting passage of vapour.

In the embodiment shown in FIGURE 5, the detector is similar to that shown in FIGURES 1 to 4, and parts "of the cooler unit similar to those in FIGURES 1 to 4 carry the same reference numerals.

In this case however, an exhaust tube 40 extends through a sealed aperture in the diaphragm 25 and has its one end secured to the central part of the end 23 on the opposite side to the detector. A side aperture 41 is formed in the one end of the tube 40 and prevents closure of that end. Inside the compartment 27, the tube 40 is bent and passes radially through a German silver bush 31 in a peripheral hole in the part 22 and a similar aligned bush 32 in a peripheral hole in the part 10. Communication between the compartment 26 and the exterior of the detector cell is thus afforded, all the connections being sealed.

A metal transfer tube 42 extends through another sealed aperture in the diaphragm 25 to afford communication between the compartments 26 and 27 and has its one end secured to the central part of the end 23 on the opposite side to the detector. A side aperture 43 is formed in the one end of the tube 28 and prevents closure of that end. The other end of the tube 42 is bent around the exhaust tube 40 in the compartment 27 so that its open end remote from the end 23 of the corn partment 26 lies centrally of the unit.

The exhaust tube 40 and transfer tube 42 are brazed together in heat exchange relationship along their lengths.

Besides the tubes 40 and 42, the compartments 26 and 27 also contain packings 44 and 45 of silica or glass wool.

The transfer tube 42 is narrow so as to set up a restriction to the passage of coolant as compared to the exhaust tube 40, which is comparatively wide.

The cooler unit is filled with liquid coolant, such as Freon 1'3, Freon 22, or Freon 12, which boils at a desired low temperature at an ambient pressure corresponding to that likely to be encountered when cooling it required.

The filling takes place in the same manner as with the first embodiment, and the exhaust tube 40 is then sealed with a frangible seal, for example in the form of the glass bulb 38. The container of the unit is now sealed and substantially filled with liquid coolant under a pressure equal to the vapor pressure of the coolant at the highest ambient temperature likely to be encountered in order to prevent expansion problems. The detector cell is evacuated as thoroughly as possible.

It will be understood that the central location of the transfer tube assists passage of cool-ant even under high rotational accelerations. The side apertures 41 and 43 are disposed in different directions to improve the flow of coolant past the end to be cooled. The flow of cold vapor through the exhaust tube helps to cool the coolant passing along the transfer tube.

The evacuation of the cell surrounding the cooler unit is advantageous as this thermally isolates the unit from its surroundings except for the inlet and exhaust tubes.

The arrangement of the two compartments, the transfer tube and the exhaust tube, enables the cooler unit to operate in any spatial position and under considerable acceleration forces. The unit, once sealed, is capable of storage over a long period of time and subsequent use.

What we claim is:

1. A cooler unit comprising a sealed container divided into two compartments, liquid coolant in each compartment, a transfer tube within the container extending between the two compartments and placing the compartments in communication with each other, a liquid flow restricting packing in at least one of said compartments, an exhaust tube connecting said one compartment to the exterior of said container, said tube extending through the other compartment of said container and means normally closing the exhaust tube and operable to place the interior of said one compartment in communication with the exterior of said container, said transfer tube having a means positioned on the end extending into said one compartment to restrict the flow therethrough relative to the flow afforded to the exhaust tube.

2. A cooler unit according to claim 1 including a closable inlet pipe opening from the exterior of said container to the interior of the other of said two compartments.

3. A cooler unit comprising a sealed container having a wall portion to be cooled, a partition within said container dividing said container into two compartments, liquid coolant in each compartment, said wall portion being associated with and at least partly bounding one of said compartments, a liquid flow restricting packing in at lea-st said one compartment, an exhaust tube connecting the interior of said one compartment to the exterior of the container, said tube extending through the other compartment of said container, means norm-ally closing said exhaust tube externally of said container and operable to place the interior of said one compartment in communication with the exterior of said container and a transfer tube extending through said partition in a liquid-tight manner permanently to place said two compartments in communication with each other, said transfer tube having a means positioned on the end extending into said one compartment to restrict the flow of fluid therethrough relative to the flow afforded to the exhaust tube.

4. A cooler unit according to claim 3 wherein said transfer tube is secured at one end to said wall portion and is formed with at least one opening in the wall thereof to ensure communication between said two compartments.

5. A cooler unit comprising a sealed container having a wall portion to be cooled, a partition within said container dividing said container into two compartments, liquid cool-ant in each compartment, said wall portion being associated with and bounding one of said compartments, at liquid flow restricting packing in at least said one compartment, an exhaust tube connecting the exterior of said container through the other of said two compartments and through said partition in a liquidtight manner to the interior of said one compartment, frangi'ble closure means normally closing said exhaust tube externally of said container and a transfer tube extending through said partition in a liquid-tight manner permanently to place said other compartment in communication with said one compartment at a location adjacent to said wall portion, said transfer tube having a means positioned on the end extending into said one compartment to restrict the flow of fluid therethrough relative to the flow afforded to the exhaust tube.

6. A cooler unit according to claim 5 wherein said other compartment is shaped to be substantially symmetrical about an axis and said transfer tube opens to said other compartment on said axis and is connected to said exhaust tube in heat exchange relationship.

7. A cooler unit comprising a sealed container having a wall portion to be cooled, an evacuated envelope, a transparent closure to said envelope disposed to allow radiations derived externally of said envelope to fall upon said Wall portion, a partition Within said container dividing said container into tWo compartments, said wall portion at least partly bounding one of said compartments, liquid coolant in each compartment a liquid flow restricting packing in at least said one compartment, an exhaust tube connecting the exterior of said envelope to the interior of said one compartment, said tube extending through the other compartment of said container,

References Cited by the Examiner UNITED STATES PATENTS 1,057,052 3/1913 Guye 6242 1,515,119 11/1924 Josephson 62514 2,515,092 7/ 1950 Miller 677.1 2,566,301 9/1951 Albert 62514 2,791,104 5/1957 Duz 62514 2,818,717 1/1958 Morris 677.1

FOREIGN PATENTS 7,773 1898 Great Britain.

LLOYD L. KING, Primary Examiner.

SAMUEL BOYD, SAMUEL FEINBERG, Examiners.

BENJAMIN A. BORCHELT, R. F. STAHL,

Assistant Examiners. 

1. A COOLER UNIT COMPRISING A SEALED CONTAINER DIVIDE INTO TWO COMPARTMENTS, LIQUID COOLANT IN EACH COMPARTMENT, A TRANSFER TUBE WITHIN THE CONTAINER EXTENDING BETWEEN THE TWO COMPARTMENTS AND PLACING THE COMPARTMENTS IN COMMUNICATION WITH EACH OTHER, A LIQUID FLOW RESTRICTING PACKING IN AT LEAST ONE OF SAID COMPARTMENTS, AN EXHAUST TUBE CONNECTING SAID ONE COMPARTMENT TO THE EXTERIOR OF SAID CONTAINER, SAID TUBE EXTENDING THROUGH THE OTHER COMPARTMENT OF SAID CONTAINER AND MEANS NORMALLY CLOSING THE EXHAUST TUBE AND OPERABLE TO PLACE THE INTERIOR OF SAID ONE COMPARTMENT IN COMMUNICATION WITH THE EXTERIOR OF SAID CONTAINER, SAID TRANSFER TUBE HAVING A MEANS POSITIONED ON THE END EXTENDING INTO SAID ONE COMPARTMENT TO RESTRICT THE FLOW THERETHROUGH RELATIVE TO THE FLOW AFFORD TO THE EXHAUST TUBE. 